Consolidated Statements of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues
Premiums									$ 36,361	$ 27,071	$ 26,157
Universal life and investment-type product policy fees									7,806	6,028	5,197
Net investment income									19,606	17,511	14,741
Other revenues									2,532	2,328	2,329
Net investment gains (losses):
Other-than-temporary impairments on fixed maturity securities									(924)	(682)	(2,432)
Other-than-temporary impairments on fixed maturity securities transferred to other comprehensive income (loss)									(31)	212	939
Other net investment gains (losses)									88	62	(1,408)
Total net investment gains (losses)									(867)	(408)	(2,901)
Net derivative gains (losses)									4,824	(265)	(4,866)
Total revenues	16,746	20,457	17,148	15,911	12,690	12,338	14,139	13,098	70,262	52,265	40,657
Expenses
Policyholder benefits and claims									35,457	29,185	28,003
Interest credited to policyholder account balances									5,603	4,919	4,845
Policyholder dividends									1,446	1,485	1,649
Other expenses									17,730	12,764	10,521
Total expenses	15,225	15,152	15,430	14,429	12,710	11,953	11,775	11,915	60,236	48,353	45,018
Income (loss) from continuing operations before provision for income tax									10,026	3,912	(4,361)
Provision for income tax expense (benefit)									3,075	1,165	(2,025)
Income (loss) from continuing operations, net of income tax	1,127	3,571	1,199	1,054	66	317	1,536	828	6,951	2,747	(2,336)
Income (loss) from discontinued operations, net of income tax	25	5	31	(41)	19	3	11	6	20	39	58
Net income (loss)	1,152	3,576	1,230	1,013	85	320	1,547	834	6,971	2,786	(2,278)
Less: Net income (loss) attributable to noncontrolling interests	(4)	(6)	(7)	7	3	4	(10)	(1)	(10)	(4)	(32)
Net income (loss) attributable to MetLife, Inc.	1,156	3,582	1,237	1,006	82	316	1,557	835	6,981	2,790	(2,246)
Less: Preferred stock dividends	31	30	31	30	31	30	31	30	122	122	122
Preferred stock redemption premium	0	0	0	146	0	0	0	0	146	0	0
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 1,125	$ 3,552	$ 1,206	$ 830	$ 51	$ 286	$ 1,526	$ 805	$ 6,713	$ 2,668	$ (2,368)
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders per common share:
Basic	$ 1.04	$ 3.35	$ 1.11	$ 0.82	$ 0.03	$ 0.33	$ 1.84	$ 0.97	$ 6.32	$ 2.98	$ (2.96)
Diluted	$ 1.04	$ 3.33	$ 1.10	$ 0.82	$ 0.03	$ 0.32	$ 1.83	$ 0.96	$ 6.27	$ 2.96	$ (2.96)
Net income (loss) available to MetLife, Inc.'s common shareholders per common share:
Basic	$ 1.06	$ 3.35	$ 1.14	$ 0.78	$ 0.05	$ 0.33	$ 1.85	$ 0.98	$ 6.34	$ 3.02	$ (2.89)
Diluted	$ 1.06	$ 3.33	$ 1.13	$ 0.78	$ 0.05	$ 0.32	$ 1.84	$ 0.97	$ 6.29	$ 3.00	$ (2.89)
Cash dividends declared per common share									$ 0.74	$ 0.74	$ 0.74